1. Field of the Invention
This invention relates to the field of safety apparatus in hydrogen processing equipment in general, and in particular, to the prevention of explosions in laboratory scale hydrogen gas diffusion purification units.
2. Description of Prior Art
Hydrogen gas is an essential element in many industrial and laboratory processes. Hydrogen must be generated, and in many instances, can only be utilized in extremely pure form. Hydrogen gas is explosive when mixed with air, in concentrations of approximately 40,000 parts per million (ppm) and above.
In the smaller-than-industrial scale of the laboratory, the purification of hydrogen gas is often accomplished by a diffusion cell, wherein dirty or impure hydrogen is passed through a series of silver-palladium tubes at an elevated temperature.
Although hydrogen gas sensors and detectors, in and of themselves, have been known for some time, and although the detection of hydrogen gas has been used in various environments, purification units for hydrogen, as used on a laboratory scale, nevertheless frequently explode. Considering that persons operating such units are expected to exhibit certain levels of proficiency in laboratory skills, such explosions take place with surprising frequency. Such units are often run for long periods of time, and are frequently left unattended.
Hydrogen gas need not leak very long before becoming sufficiently concentrated to become explosive or likely to catch fire. Moreover, diffusion purification units utilize cells operating at temperatures of approximately 750.degree. F., and are incorporated into housings or cabinets. Even a leak from without the unit could be the cause for an explosion. Leaks can be caused by loose fittings, by a brittleness in the tubing caused by the hydrogen gas flow and by the corrosive waste products.
For the very first time, and despite the existence of hydrogen gas detectors of various forms of some time, this invention provides a method and apparatus by means of which hydrogen gas explosions in laboratory scale hydrogen purification units can be virtually eliminated.